Winding yarn



April 25, 1967 G. HARDEVE 3,315,904

WINDING YARN Filed Oct. 19, 1964 2 Sheets-Sheet 1 April 25, 1957 HARDEE 3,315,904

WINDING YARN Filed Oct. 19, 1964 2 SheetsQiheet 2 600? TRAVERSE CPM. F/GS 500- I I I l I STA/W 2 4 6 a /0 x2 OOFF MAX MW% W A tforneyS chanical limitations of the particular traverse other hand,

United States Patent 3,315,904 WINDING YARN Glyndwr Hardee, Glascoed, England, assignor to British Nylon Spinners Limited, Pontypool, England Filed Oct. 19, 1964, Ser. No. 404,761 Claims priority, application Great Britain, Oct. 22, 1963,

41,57 9/ 63 i 7 Claims. (Cl. 242-18) The invention concerns improvements in or relating to winding yarns.

In the specification the term yarn is to be considered as relating to all funicular structures of a textile nature, whether composed of staple fibres or continuous filaments and it is to be considered as including monofilaments.

A desirable form of yarn package into which yarn may be wound is a cheese, such being a cylindrical-bodied, straight ended package wound on a bobbin such as a cyl-indrical tube. The bobbin requires no end flanges although the cheese has no, or very slight, taper at either end. For economic reasons it is often desirable to wind large cheeses from yarn which is being forwarded at high speeds.

A cheese is formed by rotating the bobbin onto which the yarn is wound, and by laying the yarn thereon in layers of helical coils, the layers being produced by reciprocation of the approaching yarn to and fro axially of the bobbin by means of a traverse guide to which the required traverse motion is imparted.

Rotation of the bobbin may be either by direct drive of the spindle thereof, or by surface-drive from a drive roll held in contact with the yarn wound on the bobbin.

In the former case, when the yarn is forwarded to the wind-up at a constant speed (as in most textile processes) it is necessary to adjust the drive of the spindle so that its rotational speed is gradually reduced during the winding of a package, so as to maintain constant the speed at which the yarn is taken up by the package of gradually increasing diameter.

In the latter case of surface driving, is self-adjusting as the surface speed of main constant whatever its diameter.

In order to obtain the required angle of lay of the yarn to form a stable cheese, the yarn has to be traversed at a suitable speed, depending upon the yarn take-up speed. The maximum speed of traverse is dependent on the medesign, and therefore the yarn take-up speed may be restricted.

It is known to wind cheeses either at a so-ca-lled constant' wind ratio or at a substantially constant traverse speed. The former method of winding involves maintainthe wind-up speed the cheese will ret ing constant the number of coils wound per traverse cycle (this number is usually called the wind ratio) so that as the rotational speed of the wind-up spindle is reduced during the winding of a package to maintain the surface speed constant, so is the speed of traverse reduced. A constant wind ratio can be chosen to avoid the occurrence of ribbon-winding or honeycomb-winding. On the if the traverse speed is maintained constant as the rotational speed of the spindle is reduced, ribbonwinding or more seriously honeycomb-winding may occur in certain regions of the package unless means are taken to avoid it. Such means may involve the periodic variation of the speed of traverse by a small amount, e.g. about the mean, a number of times during the winding of the cheese.

3,315,904 Patented Apr. 25, 1967 We have found that neither of the above known methods of winding cheeses is wholly satisfactory when synthetic polymer yarns are cheese-wound after drawing. With the constant wind ratio method of winding, bulging of the ends of the cheese occurs if the wind ratio is too high. If the wind ratio is too low, there is undercutting near the bobbin, and hard edges on the outside of the cheese together with dishing of the cylindrical surface of the cheese. With the constant traverse rate method of winding, the high traverse speed which is necessary if bulging is to be minimised, also leads to hard edges and dishing and to yarn being laid so as to slip wholly or in part beyond the ends of the cheese (overthrown ends).

Bulging is usually greatest at about a quarter by weight of the Winding, and is present up to and somewhat beyond the mid point by weight of the winding. It results from the contraction of the outer layers on those inner layers which are not constrained by the bobbin. Bulging is unsightly and can lead to defective withdrawal of the yarn from the cheese.

Overthrown ends are to .be avoided as they are likely to lead to breakage or filamentation of the yarn during takeoff.

Undercutting of the cheese, involving the initial layers of yarn being of less length than the mean length throughout the cheese, is again unsightly and may lead to withdrawal troubles.

Having now stated what we believe to be the cause of bulging, undercutting and overthrown ends, we have invented a new method of winding cheeses wherein the rate of traverse is programmed, is. varied systematically in relation to the winding speed, in a way such that the tendency to give raise to these defects is minimised.

According to the invention a method. of winding yarn into the form of a cheese, as hereinbefore defined, comprises winding-up the yarn on a bobbin that is rotated at a gradually decreasing rotational speed throughout the period of winding, and, independently of said winding up, traversing the approaching yarn to and fro axially of the bobbin to lay the yarn in a package of layers of helical coils, the rate of traversing being varied in such a way that it is not constant throughout the period of winding and that it attains the maximum rate at a time after about 15% and before about by weight of the yarn in the final package has been wound.

According to another aspect, the invention comprises a cheese, as herein before defined, consisting of layers of helical coils wound in a package, the helix angle of some at least of the coils in those layers which lie between about the first 15% and about the last 25%, by weight of the yarn in the package being at least as great as that of any other of the coils in the package and greater than that of the coils in the said first 15%.

Preferably, the rate of traverse is gradually (i.e. in the shape of a smooth curve in a graph plotting traverse speed against time or against weight of yarn wound) increased to reach a maximum around the time when a third of the package, by weight, has been wound, and thereafter is gradually decreased to nearly the same value at the time of doif, as it was at the start of winding. However, such rate of increase and decrease may be linear if some simplification of the mechanism may result. In certain cases some improvement in package shape may be obtained even if the rate of traverse is maintained at the maximum for the period of winding after the prescribed time.

The above-defined invention results from our finding that bulging can be cured by arranging for the maximum traverse rate to occur at about that point in the winding where the tendency to bulge is greatest. At the highest traverse rate, the effective stroke length of the traverse (from the point-of-view of the length of the layers of yarn wound) will be least (for a given traverse guide-topackage distance), owing to the lag of the yarn behind the movement of the traverse guide: and furthermore, because the yarn is then in a more open helix, i.e. the helix angle of the coils is greater, the retractive forces in the yarn can more easily prevent axial spreading of the layer. Naturally, in this context, it should be understood that the helix of the coils at the ends of the layers will be varying between one direction and the other; and therefore the references to helix angle do not relate to the angles in those ends.

Similarly, initial undercutting can be cured by arranging for the traverse rate initially to be low, because at low traverse rates the effective stroke length of the traverse will be nearer to the actual stroke length of the traverse guide.

The above remarks about effective traverse stroke length apply strictly only when the distance of the traverse guide from the surface of the package is maintained constant throughout the wind. Although this is the desirable stateof-affairs for accurate control of high-speed winding, my invention is not to be regarded as being limited to such a fixed distance being maintained, as variation of the distance, either of a short-term or along-term variety, may be of some added advantage in producing stable, straightsided cheeses under some conditions of processing.

A winding programme in which a gradual increase in traverse speed to a maximum, followed by a gradual decrease therefrom is used, has the further advantage that it leads to a reduction of wear and tear on the traverse mechanism, which is likely to be working close to its mechanical limits.

The extent of traverse rate variation required, i.e. the starting rate and the maximum rate, have to be determined by experiment, and these variables will depend on the denier of the yarn, the speed at which the yarn is wound, the length of traverse stroke, the diameter of the bobbin on which the yarn is wound, and the weight of yarn required in a full package.

The required programming of the traverse rate can be effected by various means, e.g. by driving the traverse guide by a separate motor from that driving the spindle and by varying the speed of this separate motor by wellknown means, as, for instance, a cam. Alternatively, the traverse could be driven from the spindle motor through a P.I.V. gearbox, suitably programmed.

The invention has proved to be of especial value in winding large cheeses of continuous filament nylon yarn at high speeds on the drawing machine. Such a process is desirable for economic reasons and is particularly difficult to achieve in the case of lower denier yarns, such as 60/20 nylon.

The winding of such yarns can take place either with a surface drive or a direct drive to the spindle, in the latter case with provision for the reduction of the speed of the drive in order to compensate for package growth. In both cases ribbon-breaking is necessary to avoid patterning at regions of the package during the period of winding.

The above-mentioned 60 denier nylon yarn has been wound into stable 6 lb. cheeses having very slightly tapered ends, according to the following condition:

Yarn speed as delivered by draw rolls-42,000 feet/minute Nominal traverse stroke length- /2 inches Initial traverse speed-200 cycles/ minute Maximum traverse speed-550 cycles/minute Final traverse speed-375 cycles/minute Maximum traverse speed attained-Vs way through the winding The invention will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is a frontal view of yarn being wound on a cheese;

FIGURE 2 is a side view of such winding;

FIGURE 3 is a diagram of a cheese showing bulging sides, wound according to the prior art;

FIGURE 4 is a diagram of a cheese with a dished sides, wound according to the prior art;

FIGURE 5 is a diagram of a cheese with straight sides and a flat surface, wound according to the invention;

FIGURE 6 is a graph of traverse speed against time for an embodiment of the invention;

FIGURE 7 is the cam profile for varying this speed of traverse according to that graph.

FIGURES l and 2 show a cheese wind-up on a nylon drawtwister, in diagrammatic form. Drawn nylon yarn Y is forwarded from draw roll 1 and is wound in the form of cheese 3 on a bobbin as, for instance, a cylindrical former 5. The cheese is rotated by surface drive from drive roll 7. The yarn is traversed by traverse guide 9 which is reciprocated across the width of the cheese in a horizontal slot in traverse cam box 11. A traverse roll inside the cam box and having a. helical groove therein for driving the traverse guide to and fro is rotated by motor 13.

According to the prior art methods of cheese winding, and as referred to hereinbefore, if winding is carried out at a constant high wind ratio or at a constant low traverse speed then bulging sides as shown at 15 in FIGURE 3 tend to result, and if winding is carried out at a constant low wind ratio or at a constant high traverse speed then as shown in FIGURE 4 this surface of the cheese tends to be dished, between hard edges 17, and the cheese is undercut, at 19, near to the bobbin.

In contradistinction, the cheese shown in FIGURE 5, which is indicative of one wound according to the invention, has straight, slightly tapered sides and a flat surface.

The graph of FIGURE 6 shows how the rate of traverse may be gradually increased to a maximum at about /3 of the total winding time of the cheese and then gradu-- ally reduced.

FIGURE 7 shows the shape of cam for imparting such a programme to the traverse motor, according to known techniques.

What I claim is:

1. A method of winding yarn into a cylindrical-bodied, straight-ended yarn package Wound on a bobbin comprising, winding yarn in layers of helical coils on a bobbin which is rotated at a gradually decreasing rotational speed throughout the period of winding traversing the yarn to and fro axially of the bobbin at a rate that is not constant throughout said period of winding by increasing the rate of traversing from its initial rate so that it attains the maximum rate at a time after about 15% and before about by weight of the yarn in the final package has been wound.

2. A method according to claim 1 further comprising gradually decreasing the rate of traversing after the maximum rate has been obtained.

3. A method according to claim 1 in which the rate of traversing is gradually increased to the maximum at the time when about one third by weight of the yarn in the final package has been wound, and thereafter gradually decreasing the rate of traversing.

4. A cylindrical-bodied, straight-ended yarn package wound on a bobbin in layers of helical coils, characterised by the helix angle of the coils in those layers which lie between about the first 15% and about the last 25% by weight of the yarn in the package is at least as great as the helix angle of any other of the coils in the package and is greater than the helix angle of the coils in the said first 15 5. A yarn package according to claim 4 in which the first-mentioned helix angle is also greater than that of the coils in the said last 25% by weight of yarn in the package.

6. A yarn package according to claim 4 in which the helix angle of the coils gradually increases throughout the first layers of the package to the maximum angle in those layers at the end of about the-first one-third by weight of yarn in the package, and then gradually decreases throughout the subsequent layers.

7. A yarn package according to claim 6 having very 1O slightly tapered ends and consisting of drawn nylon yarn.

References Cited by the Examiner UNITED STATES PATENTS Mitchell 242178 Abbott 242-17 8 Beeftink 242-l8 Noordenbos 242-48 Engelman 242-l76 X STANLEY N. GILREATH, Primary Examiner. 

1. A METHOD OF WINDING YARN INTO A CYLINDRICAL-BODIED, STRAIGHT-ENDED YARM PACKAGE WOUND ON A BOBBIN COMPRISING, WINDING YARN IN LAYERS OF HELICAL COILS ON A BOBBIN WHICH IS ROTATED AT A GRADUALLY DECREASING ROTATIONAL SPEED THROUGHOUT THE PERIOD OF WINDING TRAVERSING THE YARN TO AND FRO AXIALLY OF THE BOBBIN AT A RATE THAT IS NOT CONSTANT THROUGHOUT SAID PERIOD OF WINDING BY INCREASING THE RATE OF TRAVERSING FROM ITS INITIAL RATE SO THAT IT ATTAINS THE MAXIMUM RATE AT A TIME ABOUT 15% AND BEFORE ABOUT 75% BY WEIGHT OF THE YARN IN THE FINAL PACKAGE HAS BEEN WOUND. 